#include "stm32f10x.h"
void delay_nms(u16 time);
void TIM3_PWM_Init(u16 arr, u16 psc);

int main() {
    u16 led0pwmval = 100;
    u8 dir = 1;

    TIM3_PWM_Init(899, 0);  //不分频。PWM频率=72000/(899+1)=80Khz
    while (1) {
        delay_nms(10);
        if (dir)
            led0pwmval++;
        else
            led0pwmval--;
        if (led0pwmval > 200) dir = 0;
        if (led0pwmval == 0) dir = 1;
        TIM_SetCompare2(TIM3, led0pwmval);
    }
}

void RCC_Configuration() {
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);  //
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB | RCC_APB2Periph_AFIO, ENABLE);
}

void GPIO_Configuration() {
    GPIO_InitTypeDef GPIO_InitStructure;

    GPIO_PinRemapConfig(GPIO_PartialRemap_TIM3, ENABLE);  // 重映射到PA7 --> PB5
    //设置该引脚为复用输出功能,输出TIM3 CH2的PWM脉冲波形
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;        // TIM_CH2
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;  //复用推挽输出
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

    GPIO_SetBits(GPIOB, GPIO_Pin_5);
}

void TIM_TimeBaseConfiguration(u16 arr, u16 psc) {
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    //设置在下一个更新事件装入活动的自动重装载寄存器周期的值 80K
    TIM_TimeBaseStructure.TIM_Period = arr;
    //设置用来作为TIMx时钟频率除数的预分频值  不分频
    TIM_TimeBaseStructure.TIM_Prescaler = psc;
    //设置时钟分割:TDTS = Tck_tim
    TIM_TimeBaseStructure.TIM_ClockDivision = 0;
    // TIM向上计数模式
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    //根据TIM_TimeBaseInitStruct中指定的参数初始化TIMx的时间基数单位
    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
}

void TIM_OCInitConfiguration() {
    TIM_OCInitTypeDef TIM_OCInitStructure;
    //选择定时器模式:TIM脉冲宽度调制模式2
    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;
    //比较输出使能
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    //设置待装入捕获比较寄存器的脉冲值
    TIM_OCInitStructure.TIM_Pulse = 0;
    //输出极性:TIM输出比较极性高
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    //根据TIM_OCInitStruct中指定的参数初始化外设TIMx
    TIM_OC2Init(TIM3, &TIM_OCInitStructure);
}

// PWM输出初始化
// arr：自动重装值
// psc：时钟预分频数
void TIM3_PWM_Init(u16 arr, u16 psc) {
    RCC_Configuration();
    GPIO_Configuration();
    TIM_TimeBaseConfiguration(arr, psc);
    TIM_OCInitConfiguration();

    TIM_CtrlPWMOutputs(TIM3, ENABLE);  // MOE 主输出使能

    TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);  // CH2预装载使能

    TIM_ARRPreloadConfig(TIM3, ENABLE);  //使能TIMx在ARR上的预装载寄存器

    TIM_Cmd(TIM3, ENABLE);  //使能TIM1
}

void delay_nms(u16 time)  //延时子程序
{
    u16 i = 0;
    while (time--) {
        i = 12000;  //自己定义
        while (i--)
            ;
    }
}
